The most common and most likely answer to this crossword clue is the 8 letter word SEETHING
I've seen this crossword clue in The Sunday Telegraph
S
E
E
T
H
I
N
G
More clues leading to the result SEETHING
- Notice obsession making one very angry
- Observe article, furious
- Furious to discover affair
- Understand obsession is coming to the boil?
- Understand an object could get you in a state
- Extremely angry to discover affair
- Witness affair, furious
- Understand and object, being very angry
- Object after getting notice, being really mad
- Furious, grasp object
Buddy explains!

The straight part
We know that "furious" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case furious = seething.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SEETHING mean?
SEETHING verb- To boil.
- (of a liquid) To boil vigorously.
- (of a liquid) To foam in an agitated manner, as if boiling.
- (of a person) To be in an agitated or angry mental state, as if boiling.
- (of a place) To buzz with activity.
- The action of the verb to seethe.
- Boiling, bubbling
- Angry, livid.